1. Field of the Invention
The present invention is related to a series type fan device and particularly to assembling structure of two fans in series.
2. Brief Description of the Related Art
Due to electronic components being kept updated and the users keeping to create new demands, problem of heat generation arises along with enhanced effect, treating speed and power too.
Especially in the computer, North bridge chips is easy to produce high temperature too while the performance is enhanced in addition to the central processing unit (CPU) on the main board. The performance of preceding heat generating components is affected seriously if the heat is not removed rapidly and even the life spans thereof becomes shorter accordingly. In order to remove the heat from preceding heat generating components and achieve best performance thereof and prolong the life spans thereof, a heat dissipation device is usually used to attain purpose of heat dissipation. The most popularly used heat dissipation device is the fan and the radiator because of their being conveniently used and lower costs. This is why the manufacturers are interested in developing and researching the fan and the radiator. As for application of cooling fan, in order to dissipate heat from heat generating components effectively, air flow rate of the cooling fan is increased to attain higher heat dissipation efficiency. There are two ways for increasing the air flow rate in which one is to increase size of the fan and the other is to increase rotational speed of the fan. However, the size of the fan is limited with restricted available space and the rotational speed of the fan is limited with the performance of motor. Thus, two identical fans are used to join together in series to increase air flow rate and air pressure for enhancing the hat dissipation efficiency.
Taiwan Patent Official Gazette No. 481434, which is entitled COOLING DEVICE FOR CENTRAL PROCESSING UNIT, discloses a cooling device especially for CPU and the cooling device includes radiation fans and at least two fans. The characteristics of the cooling device is in that the first and second fans are joined in series and a plurality of joining posts are disposed between the two fans to increase pressure of large amount dragged air flow during the radiation fins absorbing the high heat of CPU so as to enhance effects of cooling, temperature lowering and dissipation rate.
The preceding prior art further provides that each of the two fans at the four corners thereof has a through hole respectively for the two fans being fixedly attached to the radiation fins with screws.
However, a problem of the two fans being associated with screws in practice is in that the screws are fastened at a lateral side of one of the two fans so that force exerting points are at the lateral side instead of joining surfaces between the two fans and it results in insufficient joining force to create noise during the fans rotating. In addition, fluid can escape from the clearance between the joining surfaces to influence the air flow rate and degrade the effect of heat dissipation.
Referring to FIGS. 1 to 3, a conventional improved series type fan device includes two fans. The first fan 1 includes a fan frame 11 and a fan wheel 12 disposed in the fan frame 11. The fan frame 11 at two lateral sides thereof has an inlet 111 and an outlet 112 respectively and four corners of the fan frame 11 are provided with a through hole 113 for being passed through with a screw respectively. The periphery of the fan frame 11 at the outlet 112 side thereof is provided with a projective engaging part 114. The second fan 2 includes a fan frame 21 and a fan wheel 22 disposed in the fan frame 21. The fan frame 21 at two lateral sides thereof provides an inlet 211 and an outlet 212 respectively and four corners of the fan frame 21 are provided with a through hole 213 for being passed through with the screw 3. The periphery of the fan frame 21 at the inlet 212 side thereof is provided with a receiving part 214 corresponding to the engaging part 114 of the first fan 1. The first and second fans can be joined to each other in series by way of the engaging part 114 fitting with the receiving part 214 and the screw 3 passing through the through holes 113, 213 respectively.
However, the preceding conventional improved series type fan device still has a problem inside that it is difficult to detach the engaging part 114 from the receiving part 214 unless a tool such as a screw driver to remove the engaging part 114 from the receiving part 214 with force while the first fan 1 is separated from the second fan. Hence, it leads a lot of inconvenience to the user.